The present invention relates to a variable speed conveyor apparatus, and more particularly to the precise handling of a variable speed chain and apparatus including such a chain.
In continuous production operations, or in performing operations of a repetitive nature on one or more articles in succession, it is convenient to have some form of conveyor and it is frequently necessary to transfer articles from one conveyor to another especially when certain operations have to be performed at different speeds compared with others.
An aim of the present invention is to provide a variable speed conveyor apparatus which is applicable for a number of uses according to different embodiments.
According to the present invention, there is provided a conveyor apparatus comprising a plurality of pairs of links, which are pivotally interconnected one with the other and which define an endless chain, first and second index members, and means carried by at least one link of each pair of links providing co-operating engagement with the first and second index members, the first and second index members defining an endless path along which the links are movable, means for driving the first and second members in timed relation, and respective guide means to control movement of the links from the first index member to the second index member, and from the latter to the former during conveyance around the endless path, the differential peripheral speeds of the first and second index members resulting in the links moving at differing speeds when on the two index members.
It is preferred that the first and second index members are rotatably driven and are in the form of wheels or sprockets with circumferentially spaced recesses for receiving pins interconnecting the links of the chain. The respective guide means for controlling movement of the links between the respective index members engage with the pins projecting from the links. The respective guide means control folding and unfolding of the links on their passage between the two index members. The links are arranged to be folded when on the first index member, i.e. with the ends of adjacent pairs of links lying adjacent one another and the links lying substantially side by side, and at least partially unfolded when on the second index member. A further guide may be employed to retain the pins in contact with the index members.
The apparatus may be utilised in any convenient orientation, but horizontal or vertical configurations are likely to have the most useful applications. The links can form carriers for work pieces on which operations are to be performed, for example, items requiring heat treatment.
In a more sophisticated application two sets of chain conveyor apparatus can be used in combination in spaced apart relation with a pair of links from each conveyor being interconnected by a carrier member. The carrier may be in the form of a roller which is rotatable and whose opposite ends form a pivotal connection for a respective pair of links from each chain. Such an apparatus makes use of the differential spacing and speed of the rollers as they are transferred from one index member to the other.
One application is in the handling of cloth where the apparatus may be employed to form a series of superimposed plies or folds in a length of sheet material such as cloth. To achieve this the rollers have to be rotated in a direction opposite to the direction of movement of the rollers around the endless path and at least one nip roller is required to ensure that cloth which is draped over a roller, prior to or during its transfer from co-operation with the second to the first index member to form a downwardly depending loop, is compressed with preceding loops and encouraged to be fed out from the roller path and so deposit each said loop outside the path of the rollers beneath the loop immediately preceding it.
Thus, according to another aspect of the present invention there is provided apparatus for arranging sheet material into a series of superimposed plies or folds, comprising a plurality of mutually spaced horizontal, elongate rollers arranged to describe an endless path, means carrying the rollers on said endless path comprising spaced apart chains defined by pairs of links connected one with another and entrained around and co-operating with respective first and second index members which are rotatable in synchronism at different peripheral speeds, and guide means for transferring the rollers between the index members at respective `in feed` and `off load` stations, which guide means control the folding and unfolding of the links carrying the rollers, whereby the roller being transferred from the second to first index member at the `in feed` station undergoes a marked change in direction and closes on the roller which had preceded it through the marked change in direction, means for rotating at least some of the rollers on the first index member in a direction opposite to the direction of movement of the rollers on the endless path after the roller has undergone the marked change of direction, which change in direction and the rotation of the rollers acts to control an air pocket formed between the layer of material about to be made into a loop and a previously formed ply to help make this loop, by closing each open loop, and feeding the closed loops successively out from the roller path and depositing each said loop outside the path of the rollers beneath the loop immediately preceding it.
One or more nip rollers may be employed to ensure that the roller moving from the second to the first index member closes the open loop against preceding closed loops, i.e. it or they urge the cloth into contact with the other rollers carrying the cloth.
In one embodiment a reciprocating jockey roller may be employed in addition to the nip roller(s) for a similar purpose.